1. Field of the Invention
This invention relates to a novel process for making a carpet having a secondary backing which is substantially impervious to aqueous solutions. The process involves applying a fluorochemical onto the underside of a secondary backing material. The invention also encompasses carpets made from such a process.
2. Description of Related Art
The majority of residential and commercial carpets are constructed in the following general manner. Carpet pile yarn is first inserted through a primary backing fabric to form tufts of yarn projecting from the surface of the fabric. The primary backing is then coated with a polymeric latex to lock the yarn tufts in place and to provide an adhesive for a secondary backing fabric. The latex-coated primary backing is then bonded to the secondary backing to form a laminated backing structure.
However, one problem with the above-described carpets is their susceptibility to penetration by aqueous solutions. For instance, if water or a water-based substance (soda pop, coffee, urine, etc.) is spilled onto the carpet face, it may permeate through the primary and secondary backings and onto the underlying material (carpet underpad, hardwood floors, etc.). The underlying material may become stained and deteriorate over a period of time. Mildew may also grow on the backing and underlying material.
Those skilled in the trade have considered different ways for manufacturing carpets in order to reduce the permeability of liquids through the primary backing material.
One method involves applying a fluorochemical or other water-repellent agent onto the face fiber of the carpet during the carpet-manufacturing process. In such instances, the fluorochemicals serve to reduce the wettability of the fibers in the finished carpet such that a spilled liquid will initially "bead" on the surface of the fiber. However, if the beaded liquid is not promptly removed, it will eventually be absorbed by the fibers and may penetrate through the primary backing.
Another method for making the primary backing impervious to liquids involves mixing fluorochemicals into the latex composition and then coating the primary carpet backing with the fluorochemical-containing latex.
For instance, Ucci, U.S. Pat. No. 4,643,930, discloses a carpet structure having a primary backing tufted with nylon yarns. The yarns are coated with a fluorochemical to improve the soil resistance of the carpet. The underside of the primary backing is coated with a latex containing fluorochemicals mixed therein such that the primary backing is made substantially impervious to water.
Blyth et al., U.S. Pat. No. 4,619,853 also discloses nylon carpets having a primary backing coated with a latex containing fluorochemicals mixed therein. In addition, the nylon yarns are coated with sulfonated phenol or naphthol-formaldehyde condensate to improve the stain resistance of the carpet's surface.
Ucci, U.S. Pat. No. 4,579,762 also discloses nylon carpets having a primary backing which is coated with a fluorochemical-containing latex. In this instance, the nylon yarns are made from a modified nylon polymer containing aromatic sulfonate units to improve the stain-resistance of the carpet's surface.
Although the foregoing methods may be somewhat effective for providing the primary backing with water impermeability properties, such methods may restrict the flexibility of the carpet manufacturing operation. For example, it may not be possible to continuously convert a commercial production unit in order that batches of fluorochemical-containing latex are applied to some primary backings, while batches of standard, non-fluorochemical-containing latex are applied to other primary-backings. Additionally, in some instances, stainings on carpets having impervious primary backings may be more visible since the stain will not penetrate into the primary backing, but may spread across the face of the carpet. In cases of wall-to-wall carpeting, the stains may spread into undesirable areas, such as the corners in a room. In addition, if such carpets also have a secondary backing, the latex containing the mixed fluorochemicals may reduce the adhesion between the primary and secondary backings, thus reducing the delamination strength of the carpet.
In view of the above disadvantages, it would be desirable to have a method for making the secondary backing of a carpet substantially impervious to aqueous solutions, and such a method should also be commercially flexible for the manufacturing of carpets. The present invention provides such methods as well as the resultant carpets having a secondary backing substantially impervious to aqueous solutions.